In recent years, as a method of producing a multilayer printed wiring board, a production technique using a build-up method in which resin insulating layers and conductor layers are alternately stacked on a conductor layer of an inner-layer circuit board has been drawing attention. For example, there has been proposed a method of producing a multilayer printed wiring board in which, after coating and heat-curing an epoxy resin composition on an inner-layer circuit board having a circuit formed thereon, the resulting surface is treated with a roughening agent to form an irregularly roughened surface and a conductor layer is subsequently formed by plating. Further, there has also been proposed a method of producing a multilayer printed wiring board in which an adhesive sheet of an epoxy resin composition is laminated and heat-cured on an inner-layer circuit board having a circuit formed thereon and a conductor layer is subsequently formed (see Patent Document 1).